The present invention relates to blowout preventer apparatus of the type having a radially compressible annular packing mounted within a housing chamber wherein the packing expands axially as it is radially compressed. More particularly, the present invention relates to an improvement in such blowout preventer apparatus wherein segmented end rings are provided on the packer for guiding and controlling the packing movement as it expands axially within the blowout preventer apparatus housing chamber.
Various types of blowout preventer apparatus have been developed heretofore for use in subsea as well as on land oil well installations. Exemplary thereof is the blowout preventer apparatus of the prior U.S. patent application Ser. No. 160,787 filed June 18, 1980 now abandoned entitled IMPROVED BLOWOUT PREVENTER and which is assigned the common assignee of the present application. The blowout prevent apparatus of that application includes a radially compressible annular packing mounted within a housing chamber, the housing having axially aligned upper and lower conical bores communicating with an inner bore of the annular packing. An outer packing is pressured by hydraulic fluid, in known manner, to apply a radially constricting force upon the inner annular packing which, in view of such constriction, tends to expand axially into the upper and lower conical bores provided in the blowout preventer housing end flanges forming the chamber. While other prior art blowout preventers employ solid end rings to re-enforce the ends of the packing, and to guide its movement, the end rings of the blowout preventer apparatus of said application Ser. No. 160,787 are segmented into a plurality of rigid segments which are attached to the ends of the packing in order to be individually movable axially outwardly and radially inwardly relative the housing end flange conical bores during the inner packings axial expansion under the forces of radial compression applied by the outer packing. Stop means were provided in that prior blowout preventer construction for limiting the extent of travel of the segments as they moved along the conical bore surfaces.
While the provision of segmented end rings in said prior application Ser. No. 160,787 allows for individual movement of the upper and lower segments relative to each other, even during unsymmetrical radial compression of the packing member, no means was disclosed for restricting or guiding the direction of travel of each of the segments, which as independently seated upon a web portion of the packing end, individual web portions and segments being divided by grooves in the packing therebetween. We have determined that it would be desirable to provide some means for controlling the direction of segment movement in addition to the limit on the extent of movement provided in the prior blowout preventer apparatus.